淺埋煤層不同采—充—留條件下地表沉陷控制研究
發(fā)布時間：2018-07-22 13:06
【摘要】：地下開采破壞了覆巖的原巖應(yīng)力場，并使覆巖變形以某種方式傳遞到地表。地表沉陷不但會使礦區(qū)耕地減少，而且由下沉引起的地表變形會使地表建筑物發(fā)生傾斜、開裂甚至倒塌的危險，對于淺埋大采高煤層，這種現(xiàn)象尤為突出。目前，膏體充填開采、條帶開采及置換開采是緩解地表下沉、控制沉陷的有效方法。 膏體充填不僅是一種有效的減沉方法，而且還可以有效的減少礦區(qū)的矸石堆放。膏體充填材料的力學(xué)性質(zhì)、變形性質(zhì)決定了充填開采對地表沉陷控制效果的優(yōu)劣。條帶開采中合適的采留寬度不但能有效的控制地表變形，還能在保證留設(shè)煤柱長期穩(wěn)定的基礎(chǔ)上提高煤炭采出率�；谳d荷置換理論的置換開采在合適的充填材料配比下不但能保證置換前后地表變形仍控制在建筑物I級允許值以內(nèi)，而且能最大化的置換煤柱。論文通過實驗室制備具有膨脹變形性質(zhì)的膏體材料、理論分析各減沉方法的減沉機理以及針對淺埋煤礦中三種減沉方法的數(shù)值模擬研究，系統(tǒng)的分析對比了不同材料配比下充填開采、置換開采的減沉效果并與最佳采留條件下的條帶開采進行對比。主要內(nèi)容及結(jié)果如下: (1)實驗室制備了具有膨脹特性的膏體材料，分析了膏體材料的膨脹率、抗壓強度、抗剪強度、抗拉強度、內(nèi)摩擦角、內(nèi)聚力隨膨潤土含量的變化關(guān)系。實驗表明：在膏體材料中摻入一定比例的膨潤土,可以提高充填體的膨脹率，但會降低其單軸抗壓強度，，而且較高的膨潤土摻量不利于膏體材料的和易性、流動性。當膨潤土與水泥質(zhì)量之比為0.6時，膨脹率達到2.25%，材料28d時的抗壓強度為4.85Mpa，材料為最佳配比。 (2)針對山西西部某礦的具體地質(zhì)條件，采用FLAC3D模擬軟件利用不同配比時測得的膏體材料力學(xué)參數(shù)對該礦18112工作面進行完全充填開采的數(shù)值模擬。結(jié)果表明：充填體接頂率在控制頂板及地表下沉中的影響大于充填體強度的影響，隨著膨潤土與水泥質(zhì)量之比的增加，地表變形減小，覆巖垂直應(yīng)力減小，覆巖破壞區(qū)域減小。當膨潤土與水泥質(zhì)量之比為60%時，充填體完全接頂，覆巖應(yīng)力場最接近原巖應(yīng)力分布，此時的地表變形最小，且均在建筑物I級允許值以內(nèi)。 (3)基于條帶煤柱的強度理論設(shè)計了不同采留比的條帶開采方案，模擬結(jié)果表明：采35m留30m時地表沒有出現(xiàn)波浪下沉且變形均在建筑物I級允許值以內(nèi)，煤柱安全系數(shù)最大，煤柱能保持長期穩(wěn)定性，采出率達到53.8%。模型高度方向30m以上區(qū)域覆巖處于原巖應(yīng)力狀態(tài)，而該區(qū)域以下煤柱上方存在應(yīng)力增高區(qū)，采空區(qū)上方存在應(yīng)力降低區(qū)，并且留寬越大，原巖應(yīng)力區(qū)范圍也越大。留設(shè)煤柱兩端邊緣已破壞，應(yīng)力為0MPa，從煤柱邊緣到距離兩端小于5m處煤柱只有殘余應(yīng)力，煤柱承受的最大應(yīng)力均出現(xiàn)在距邊緣5m處，煤柱中部受力最小，煤柱屈服區(qū)寬度不隨采寬的變化而改變。 (4)基于條帶開采的置換煤柱研究表明：當充填高度達到4.5m即充填體可以完全接頂時，可將30m煤柱完全置換，此時地表下沉與置換開采前幾乎相等。而當充填體不能完全接頂時，置換后地表變形值大幅增加。當留設(shè)煤柱兩端各保留5m小煤柱時，充填高度由4.3m增加到4.4m，其垂直應(yīng)力與置換前的差值逐漸減小，并且應(yīng)力變化規(guī)律與置換前相似，此時地表變形與置換前相比稍有增加，但仍小于建筑物I級允許值，說明留設(shè)的小煤柱在充填體接頂前有效的控制了頂板下沉。
[Abstract]:Underground mining destroys the original rock stress field of overlying rock and causes the overlying rock deformation to be transferred to the surface in some way. The surface subsidence not only reduces the cultivated land in the mining area, but also causes the surface deformation caused by the subsidence to cause the slope, crack and even the collapse of the surface of the surface, especially for the shallow and large coal seam. Body filling mining, strip mining and replacement mining are effective methods to mitigate surface subsidence and control subsidence.
Paste filling is not only an effective method of reducing subsidence, but also can effectively reduce the dumping of gangue in the mining area. The mechanical properties of the paste filling material and the deformation properties determine the effect of filling mining on the control of surface subsidence. The suitable mining width in strip mining can not only effectively control the surface deformation, but also guarantee the retention of the ground. On the basis of long-term stability of the coal pillar, the coal recovery rate is improved. The replacement mining based on the load displacement theory can not only ensure that the surface deformation is still within the allowable value of the I level of the building before and after the replacement, but also maximizes the displacement coal column. In this paper, the mechanism of sedimentation reduction and the numerical simulation of three methods for subsurface subsidence in shallow buried coal mine are analyzed theoretically. The analysis and comparison of filling mining under different material ratio and the comparison of the settlement reduction effect of displacement mining with the optimum mining conditions are compared. The main contents and results are as follows:
(1) a paste material with expansion characteristics was prepared in the laboratory. The expansion ratio, compressive strength, shear strength, tensile strength, tensile strength, internal friction angle, and cohesive force with the content of bentonite were analyzed. The experiment showed that a certain proportion of bentonite in the paste material could improve the expansion rate of the filling body, but it would reduce it. The uniaxial compression strength, and the higher bentonite content is not good for the paste material and the fluidity, when the ratio of the bentonite to cement is 0.6, the expansion rate is 2.25%, the compressive strength of the material 28d is 4.85Mpa, and the material is the best ratio.
(2) according to the specific geological conditions of a mine in Western Shanxi, the numerical simulation of full filling mining on the 18112 working face of the mine is carried out by using the FLAC3D simulation software. The results show that the influence of the filling roof rate on the control roof and the surface subsidence is greater than the effect of the strength of the filling body. With the increase of the ratio of bentonite to cement, the surface deformation decreases, the vertical stress of overlying rock decreases, and the failure area of overlying rock decreases. When the ratio of bentonite to cement is 60%, the filling body is fully connected to the roof, and the stress field of the overlying rock is closest to the distribution of the original rock stress, and the surface deformation is minimum at this time, and it is within the allowable value of the I grade of the building.
(3) based on the strength theory of strip coal pillar, the strip mining scheme with different recovery ratio is designed. The simulation results show that there is no wave subsidence and the deformation is within the allowable value of the building I level when the 35m is retained for 30m, the coal pillar safety factor is maximum, the coal pillar can maintain the long-term stability, and the recovery rate reaches the height direction of the 53.8%. model above 30m area. The overlying rock is in the stress state of the original rock, and there is an increasing stress area above the coal pillar below this area. There is a stress reduction area above the goaf, and the greater the width of the area, the greater the range of the stress area of the original rock. The stress of the left side of the pillar has been destroyed and the stress is 0MPa. The coal pillar is only residual stress from the edge of the coal pillar to the distance less than 5m and the pillar is subjected to the coal pillar. The maximum stress appears at 5m from the edge. The stress in the middle of the pillar is the smallest, and the width of the pillar yield zone does not change with the change of mining width.
(4) the study of replacement coal pillar based on strip mining shows that when the filling height is 4.5m, the 30m pillar can be completely replaced, and the surface subsidence is almost equal to that before the displacement mining. When the filling body can not be fully connected to the top, the deformation value of the surface after the replacement is greatly increased. When the retained coal pillar is retained at both ends of the pillar, 5m small coal is retained. In the column, the filling height is increased from 4.3m to 4.4m, and the difference between vertical stress and before replacement gradually decreases, and the variation of stress is similar to that before replacement. At this time, the surface deformation is slightly increased compared with that before replacement, but it is still less than the allowable value of the I level in the building, indicating that the small coal pillar is effectively controlled by the roof subsidence before the filling body is connected to the roof.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TD327
本文編號：2137562
[Abstract]:Underground mining destroys the original rock stress field of overlying rock and causes the overlying rock deformation to be transferred to the surface in some way. The surface subsidence not only reduces the cultivated land in the mining area, but also causes the surface deformation caused by the subsidence to cause the slope, crack and even the collapse of the surface of the surface, especially for the shallow and large coal seam. Body filling mining, strip mining and replacement mining are effective methods to mitigate surface subsidence and control subsidence.
Paste filling is not only an effective method of reducing subsidence, but also can effectively reduce the dumping of gangue in the mining area. The mechanical properties of the paste filling material and the deformation properties determine the effect of filling mining on the control of surface subsidence. The suitable mining width in strip mining can not only effectively control the surface deformation, but also guarantee the retention of the ground. On the basis of long-term stability of the coal pillar, the coal recovery rate is improved. The replacement mining based on the load displacement theory can not only ensure that the surface deformation is still within the allowable value of the I level of the building before and after the replacement, but also maximizes the displacement coal column. In this paper, the mechanism of sedimentation reduction and the numerical simulation of three methods for subsurface subsidence in shallow buried coal mine are analyzed theoretically. The analysis and comparison of filling mining under different material ratio and the comparison of the settlement reduction effect of displacement mining with the optimum mining conditions are compared. The main contents and results are as follows:
(1) a paste material with expansion characteristics was prepared in the laboratory. The expansion ratio, compressive strength, shear strength, tensile strength, tensile strength, internal friction angle, and cohesive force with the content of bentonite were analyzed. The experiment showed that a certain proportion of bentonite in the paste material could improve the expansion rate of the filling body, but it would reduce it. The uniaxial compression strength, and the higher bentonite content is not good for the paste material and the fluidity, when the ratio of the bentonite to cement is 0.6, the expansion rate is 2.25%, the compressive strength of the material 28d is 4.85Mpa, and the material is the best ratio.
(2) according to the specific geological conditions of a mine in Western Shanxi, the numerical simulation of full filling mining on the 18112 working face of the mine is carried out by using the FLAC3D simulation software. The results show that the influence of the filling roof rate on the control roof and the surface subsidence is greater than the effect of the strength of the filling body. With the increase of the ratio of bentonite to cement, the surface deformation decreases, the vertical stress of overlying rock decreases, and the failure area of overlying rock decreases. When the ratio of bentonite to cement is 60%, the filling body is fully connected to the roof, and the stress field of the overlying rock is closest to the distribution of the original rock stress, and the surface deformation is minimum at this time, and it is within the allowable value of the I grade of the building.
(3) based on the strength theory of strip coal pillar, the strip mining scheme with different recovery ratio is designed. The simulation results show that there is no wave subsidence and the deformation is within the allowable value of the building I level when the 35m is retained for 30m, the coal pillar safety factor is maximum, the coal pillar can maintain the long-term stability, and the recovery rate reaches the height direction of the 53.8%. model above 30m area. The overlying rock is in the stress state of the original rock, and there is an increasing stress area above the coal pillar below this area. There is a stress reduction area above the goaf, and the greater the width of the area, the greater the range of the stress area of the original rock. The stress of the left side of the pillar has been destroyed and the stress is 0MPa. The coal pillar is only residual stress from the edge of the coal pillar to the distance less than 5m and the pillar is subjected to the coal pillar. The maximum stress appears at 5m from the edge. The stress in the middle of the pillar is the smallest, and the width of the pillar yield zone does not change with the change of mining width.
(4) the study of replacement coal pillar based on strip mining shows that when the filling height is 4.5m, the 30m pillar can be completely replaced, and the surface subsidence is almost equal to that before the displacement mining. When the filling body can not be fully connected to the top, the deformation value of the surface after the replacement is greatly increased. When the retained coal pillar is retained at both ends of the pillar, 5m small coal is retained. In the column, the filling height is increased from 4.3m to 4.4m, and the difference between vertical stress and before replacement gradually decreases, and the variation of stress is similar to that before replacement. At this time, the surface deformation is slightly increased compared with that before replacement, but it is still less than the allowable value of the I level in the building, indicating that the small coal pillar is effectively controlled by the roof subsidence before the filling body is connected to the roof.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TD327
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